Kinetic characterization of purified laccase from Trametes hirsuta : a study on laccase catalyzed biotransformation of 1
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ORIGINAL RESEARCH PAPER
Kinetic characterization of purified laccase from Trametes hirsuta: a study on laccase catalyzed biotransformation of 1,4-dioxane Kavitha Keshava Navada . Ananda Kulal
Received: 26 November 2019 / Accepted: 26 October 2020 Ó Springer Nature B.V. 2020
Abstract Objective Laccase is one of the best known biocatalysts which degrade wide varieties of complex molecules that are both non-cyclic and cyclic in structure. The study focused on enzyme kinetics of a purified laccase from Trametes hirsuta L. fungus and its application on biotransformation of a carcinogenic molecule 1,4-dioxane. Results Laccase was purified from white-rot fungus T. hirsuta L. which showed specific activity of 978.34 U/mg after the purification fold of 54.08. The stable laccase activity (up to 16 h) is shown at 4–6 pH and 20–40 °C temperature range. The purified enzyme exhibited significant stability for 10 metal ions up to 10 mM concentration, except for Fe2? and Hg2?. The Cu2? ion induced laccase activity up to 142% higher than the control at 10 mM concentration. The laccase enzyme kinetic parameters Km was
Electronic supplementary material The online version of this article (https://doi.org/10.1007/s10529-020-03038-1) contains supplementary material, which is available to authorized users. K. K. Navada A. Kulal (&) Biological Sciences, Poornaprajna Institute of Scientific Research, Bidalur post, Devanahalli, Bengaluru Rural 562110, India e-mail: [email protected] K. K. Navada Manipal Academy of Higher Education, Manipal 576104, India
20 ± 5 lM and 400 ± 60 lM, whereas Kcat was 198.29 ± 0.18/s and 80.20 ± 1.59/s for 2,20 -azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) and guaiacol respectively. The cyclic ether 1,4dioxane (100 ppm) was completely degraded in presence of purified laccase within 2 h of incubation and it was confirmed by HPLC and GC analysis. The oxidation reaction was accelerated by 25, 22, 6 and 19% in presence of 1 mM syringaldehyde, vanillin, ABTS and guaiacol mediators respectively. Conclusions In this study, fungal laccase (a natural biocatalyst) based degradation of synthetic chemical 1,4-dioxane was reported for the first time. This method has added advantages over the multiple methods reported earlier being a natural remedy. Keywords Biodegradation 1,4-dioxane Enzyme kinetics Inhibition kinetics Laccase
Introduction Laccases (benzenediol oxygen oxidoreductases, EC 1.10.3.2) are multi-copper containing oxidoreductases and represent one of the oldest enzymes ever described (Bourbonnais and Paice 1990). It is often released in response to the nutrient depletion in the environment by the ligninolytic fungi, especially white-rot fungi (Chandra and Singh 2012; Chandra and Chowdhary
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Biotechnol Lett
2015; Kumar and Chandra 2020). Laccases are usually monomeric proteins that bring about four one-electron oxidation of the substrate and subsequent reduction of molecular oxygen to water. However, laccases require other small mol
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